Objective:To investigate the effect of aspirin on the function of endothelium-type nitric oxide synthase(eNOS) in platelets of type 2 diabetic patients. Methods:Platelets,isolated from blood of healthy human subjects and type 2 diabetic patients,were exposed in vitro to aspirin at three different concentrations(25,50,100 μmol/L) and vehicle respectively. Platelets aggregation was measured turbidimetrically with a NBC Hema Tracer 601 aggregometer. In platelets,eNOS activity was determined by the ratio of the conversion of L-[3H]-arginine to L-[3H]-citrulline. Intraplatelet cGMP,an index of bioactive NO,was measured by radioimmunoassay. Results:Compared with the vehicle,aspirin concentration-dependently decreased the platelets aggregation,increased the activity of eNOS in platelets and intraplatelet cGMP level significantly,both in healthy human control and type 2 diabetic patients. And the effect was greater in healthy human subjects than that in type 2 diabetic patients at the same concentration of aspirin. Conclusion:Aspirin can improve the function of the platelet eNOS in type 2 diabetic patients in a concentration-dependent manner.